Low-intensity DC polarization of focal cortical areas is known to alter the function of neurons in animals and humans. We are investigating the properties of this kind of brain stimulation and testing its ability to alter cognitive function in healthy subjects. We have completed a large Phase I, sham-controlled trial of DC polarization of the left prefrontal area in healthy volunteers. Results show safety even at higher intensities than those used in published modern studies and we also found a significant facilitation of word list generation with anodal current relative to sham and cathodal current. Currently, we are also testing a similar anodal current treatment for impaired fluency in patients with frontotemporal dementia. These are the first studies of their kind and the first modern human use of DC polarization in this country.